The present invention relates to a novel tab dispensing device utilized with a pneumatically or electrically powered nail gun or staple gun for providing a tab positioned to properly receive a nail or staple delivered by the gun.
Automatic staple or nail guns, powered by electricity or air pressure, are frequently utilized to staple or nail tar paper or other roofing material onto the roofs of homes and buildings. Local building codes now permit the use of wide crown staples and pneumatically driven nails to attach the tar paper or roofing material to the plywood structure of the roof. However, the staples or nails must be used in conjunction with very thin metallic or plastic tabs or discs. Essentially, each nail or staple is driven through these tabs or discs such that the upper part of the inverted U-shaped staple, or the head of the nail, remains in contact with the disc or tab surface while the legs of the staple or the shank of the nail protrude through the tab, through the tar paper or other generally waterproof building cover, and into the underlying plywood or other type of solid roof structure.
It was customary in the past for a roofer to grasp a single disc, place the disc in the appropriate location on the roof, position the powered automatic staple gun or nail gun above the disc, and then trigger the gun, to cause the expulsion of the staple or nail. The staple or nail, driven by a significantly large force, penetrates the tab or disc and the tar paper and is injected into the underlying solid roof structure. This procedure can be dangerous in that the roofers must manually handle the discs and accurately place the gun atop the disc before firing the gun. There is a possibility that the roofer may be injured by not withdrawing his or her hand from the disc prior to firing the staple or nail. Misplacement of the gun or staple or nail on top of the disc or tab requires that the roofer repeat the procedure to properly place the staple or nail in the central region of the tab or disc. Typically, several thousand staples or nails and discs are utilized on a single residential roof.
An advance in the feeding of tabs or discs to a nail gun is represented by the Zylka et al Pat. No. 5,184,752 entitled "METHOD AND APPARATUS FOR FEEDING TABS OR DISCS TO AN AUTOMATIC STAPLE OR NAIL GUN," which patent issued Feb. 9, 1993. In accordance with that device, a preformed dimpled disc is dispensed from a stack of discs as the result of a co-functioning of the Zylka et al device with the nail gun. However, the arrangement taught by Zylka et al necessitated to some extent, an alteration of the safety features provided by the manufacturer of the nail gun. In addition, the interconnection between the Zylka et al device and the nail gun adversely affects the mobility of the nail gun.
In comparison with the Zylka et al device, the instant device is not directly connected in any physical way with the safety features inherent to the nail gun, thus avoiding any compromise of the safety features relied upon by the nail gun manufacturer.
Quite significantly, the Zylka et al device requires power from an outside source, either pneumatic or electric, which involves a definite amount of setup time as well as additional expense. In contrast, only the nail gun itself, rather than the instant invention, involves the need for the application of external power.
The circular tabs utilized in the field by Zylka et al are utilized in a stacked relationship in a cylindrically shaped canister or container. Because the tabs are quite thin, the discs are rather difficult for the Zylka et al type device to separate. In attempting to overcome the problems involved in separating these thin individual tabs from the stack, Zylka et al dimpled their tabs. The dimples allow for clearance between tabs so that their shuttle device can remove one tab at a time from the stack. The dimpling process likely requires a relatively high degree of accuracy in order that the correct tolerances can be maintained. Because the instant device uses a completely different tab moving procedure, it can utilize tabs made with a wide margin of tolerance and without the need for dimpling.
The build-up of dirt and grime on exposed tool components is common in the work environment. Because of the close tolerances needed between tabs in the Zylka et al device, it is much more susceptible to the build-up of dirt and grime than would the instant device.
The tabs used by both Zylka et al and the instant invention are waterproof. However, the tabs utilized by Zylka et al are packaged in disposable cardboard canisters which are prone to damage due to hazards of the work environment such as moisture or dropping. The instant device uses a single rubber band to keep the waterproof tab strip in a packaged roll form until the time of actual use.
It is further to be noted that Zylka et al's device entails it being pushed or rolled across a nailing surface, placing the user of such device at a distinct disadvantage if he was working on a surface other than horizontal. The safety spring used on the nail gun is normally not strong enough to move the two devices apart, which causes the operator to have to pull the nail gun away from the tab device in order to cause both devices to operate. This is to be contrasted with the instant invention, which is designed to operate in a highly satisfactory manner through all positions, whether horizontal, vertical or inverted.
Other comparisons of the instant device with Zylka et al will become more apparent as the description proceeds.